Study: Best way to test for COVID-19 is nasopharyngeal swab

Editor's Note

This study by researchers from Cornell University finds that nasopharyngeal swabs taken from back inside the nostril were more effective at detecting COVID-10 than saliva tests or swabs just inside the nostril or under the tongue.

Comparing different samples from 77 patients, the researchers found that:

• Nasopharyngeal samples provided the best rate of detection, from 92% to 100%, likely because the virus replicates in the nasal turbinates in the uppermost portion of the nose.
• Detection rates from anterior nostrils and saliva specimens were slightly lower at 92% to 96% for symptomatic patients and 75% to 92% for asymptomatic patients, confirming the rationale for shortened isolation guidelines.
• Detection rates of sublingual specimens were poorer at 40% to 60% for symptomatic patients and 25% to 42% for asymptomatic patients.

Understanding the diagnostic performance of these specimens and the patterns of infectious virus shedding provides important information to control COVID-19 and refine guidelines on isolation and quarantine, the researches note.